The present invention relates generally to temperature indicators, and more particularly, to an apparatus and method to independently extend and retract a pair of temperature indictor sticks longitudinally aligned along two axes.
Temperature indicators are well known in the welding, metal fabrication, and heat treatment industries. Such products are capable of determining surface temperatures during welding and metal fabrication processes. The products have also found use in heat-treatment processes, and can determine operating temperatures of mechanical, hydraulic, and electrical systems and components, such as transformers and motors.
Initially, temperature sensing was conducted by sprinkling a few granules of a known compound on an object. When the granules melted, the desired temperature was achieved. Later, pellets were introduced to make marks similar to a chalk mark on a surface of the object rather than observing the entire pellet melt. Further improvements led from a pellet to a chalk stick, which is protected in a housing that includes an adjustable holder for positioning the temperature indicator stick relative to the housing.
One known temperature indicator includes a housing having a rimmed end and a flanged end. A temperature indicator stick is inserted into the housing through the flanged end and prevented from leaving the housing by the rimmed end. The stick also has an outer casing or holder that is threaded into the housing and encloses the flanges. The outer casing is tapered to constrict the flanges and lock the temperature indicator stick in a fixed position.
Problems exist with the current state of the art of temperature indicators. Existing holders for temperature indicators are not satisfactory. Such holders are often limited in their ability to fix the temperature indicator stick in position. Operator use of the temperature indicator stick results in pressure exerted on the end of the stick during marking which causes the stick to retract into the housing. Generally, the operator must unscrew the outer casing, reposition the temperature indicator stick, and then retighten the outer casing to continue marking objects.
Another problem is that current temperature indicators are configured to hold one temperature indicator stick, limiting temperature detection to a single temperature value. Operators desiring to detect several temperatures must carry or locate multiple temperature indicators, which is often tedious. Furthermore, since current temperature indicators are configured for a single stick, the indicator sticks are generally positioned within tubular-shaped housings that are difficult to adjust during use, especially in welding and other heat-treating processes that require an operator to wear gloves and other heat-protection equipment which limits the operator's ability to manipulate small objects. Further, many applications require two different temperature indicator sticks for testing different temperatures in a single operation. It is difficult for an operator to hold a welding gun in one hand, for example, and two temperature indicator sticks in the other hand while wearing heat-resistant gloves.
There is a need for an apparatus and method to separately fix a pair of temperature indicator sticks in position to improve an operator's ability to hold and manipulate the temperature indicator sticks to mark objects for temperature detection, and also to reduce the number of temperature indicator holders needed by operators. It would therefore be desirable to have a more efficient temperature indicator than current indicators by having a pair of temperature indicator sticks aligned along a pair of axes in a single housing and having a pair of advancement mechanisms to engage each temperature indicator stick independently.